huawei gsm handover algorithm

8/10/2019 Huawei GSM Handover Algorithm

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GSM Handover Algorithm N-1

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Copyright 2008 Huawei Technologies Co., Ltd. All rights reserved.

GSM HandoverAlgorithm

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Page2Copyright 2008 Huawei Technologies Co., Ltd. All rights reserved.

Foreword

Handover is a key technology of mobile communication system and

make continued conversation possible.

Handover algorithm in Huawei product is flexible and powerful.



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Objectives

Upon completion of this course, you will be able to:

Outline the types of handover

Master handover judgment flow

Understand algorithm of different handovers

Explain HO data configuration



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Contents

1. Introduction of Handover

2. HO Algorithm Process



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Contents





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Purposes of HO

To keep a continuous communication with a moving MS

To improve network service performance

To reduce the call drop rate

To reduce the congestion rate

Handover can maintain the communication continuity of MS which moves across different

cells and lower the call drop rate and provide better communication service.



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Classification by Reason

No DL MR Emergency HOTiming Advance (TA) HO

Interference HO

Rx_Level_Drop HO

Bad Quality (BQ) HO

Emergency HO

Enhanced Dual Band HO

Load HO

Normal HO

1

2

3

4

Classification

by

ReasonEDGE HO

PBGT HO

Layer HO

MS Fast Moving HO

Concentric Cell HO

AMR HO



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Classification by Synchronization

CELL

Case 1

Synchronous Handover: the target BTS shall not send PHY INFO message

Case 2

Asynchronous Handover: the target BTS shall send PHY INFO message

Case 3 Case 4Case 5

MSC

BSC

BTS

BSC BSC

MSC

BTS BTSBTS

BTS

NSS Network

Synchronous handover: source and target cell belong the same BTS

Asynchronous handover: source and target cell belong the different

BTS



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Classification by Equipment and

Channel

SDCCHSDCCH TCHTCH

(Direct Retry)(Direct Retry)

SDCCHSDCCH SDCCHSDCCH

IntraIntra Cell HOCell HO ((HRHRFRFR))

InterInter Cell HOCell HO

IntraIntra BSC HOBSC HO

IntraIntra MSC HOMSC HO

InterInter MSC HOMSC HO

TCHTCH TCHTCH



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Contents





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Contents


2.1 General HO Process

2.2 Measure and Measurement Result Report

2.3 Measurement Report Preprocessing

2.4 Handover Judgment

2.5 Handover Implementation



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General HO Process

MS Goes into New Dedicated Mode

MS Goes into Dedicated Mode

Measure and Measurement Result Report1

Measurement Report Preprocessing2

Handover Judgment3

Handover Implementation4



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General HO Process




Measurement Report Preprocessing2

Handover Judgment3




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The downlink measurement reportof the neighbor cell (BCCH)

Measurement Report

Uplink MR includes uplink receiving level and quality.

Downlink MR includes downlink receiving level, downlink

receiving quality of the serving cell and other downlink receiving

levels from the neighbor cells.

Serving cell

Neighbor cell

The uplink MR

The downlink MR

In dedicated mode, the system performs handover and power control judgment based on

measurement reports. The downlink MR are reported to the network via uplink SACCH

channel.

Downlink--In dedicated mode, MS reports MR via uplink SACCH channel periodically. The

report includes the receiving level, received quality, TA, power class and whether DTX isused. At the same time, MS will perform pre-synchronization to neighbor cell defined by the

system to obtain BCCH frequencies and BSIC, measure their received signal level and

report the six max. neighbor cells with the highest received signal level.

Uplink--The uplink measurement report is measured by BTS, including the receiving level

and receiving quality from the MS.

Both parts are sent by BTS to BSC for further processing at the same time.



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Measurement Report

There are two values in the measurement report: FULL MR and SUB MR.

FULL--Averaging 100 TCH bursts (except the four idle frames in the four 26-multiframes)

SUB--Averaging 12 bursts (four SACCH bursts and eight TCH bursts in specific position).

SUB should be selected when the Discontinuous Transmission (DTX) function is activated.

RXQUAL level in MR Huawei value BER behind

0 0 Less than 0.2%

1 10 0.2% ~ 0.4%

2 20 0.4% ~ 0.8%

3 30 0.8% ~ 1.6%

4 40 1.6% ~ 3.2%

5 50 3.2% ~ 6.4%6 60 6.4% ~ 12.8%

7 70 Greater than 12.8%



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Period of Measurement Report

The downlink MR is sent to BTS in SACCH uplink

The interval is 480ms/per time when MS is on TCH

The interval is 470ms/per time when MS is on SDCCH

12TCH 12TCH1SACCH 1 Idle

480ms 4 TCH Multi-frames

SACCH is a bidirectional channel.

It sends the downlink measurement report to BTS in uplink SACCH.

It sends SYS.INFO. 5 and SYS. INFO. 6 to MS in downlink SACCH.

1. The SACCH measurement report period varies with the channel

occupied by MS in dedicated mode.

2. When associated with SDCCH, SACCH measurement period is 470ms,

this is because there is an entire SACCH message block in 2 SDCCH

51-multiframes.

3. When associated with TCH, SACCH measurement period is 480ms, this

is because there is an entire SACCH message block in 4 TCH 26-

multiframes

A complete measurement report is formed by four consecutive SACCH bursts. In SDCCH

channel the four bursts are transmitted continuously. In TCH channel there is only oneSACCH burst in each 26-multiframe, therefore only four 26-multiframe can constitute a

complete measurement report.



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General HO Process



Measurement Report Preprocessing

Handover Judgment3



2



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MR Preprocessing

MR Preprocessing

Interpolation

Recover the lost

measurement report

Filtering

Smooth the instantaneous

fading point

MR preprocessing consists of two steps: interpolation and filtering.



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MR Interpolation

MR

MR

No. n

No. n+4

Continu

ousMRFlow

MRMR

MR

Missing by

some reasons

MR Interpolation recover the lost measurement report

BTS may fail to receive the MR from MS, and it needs to recover the lost measurement reports. If the

lost MR amount is within the allowed range (Allowed MR Number Lost), then recovers the lost MR

according to the specific algorithm.

Service cell: linear algorithm

Neighboring cell: the lowest value defined in GSM specification (-110dBm)

The continuity of measurement report is judged by measurement report number. Each

measurement report has a serial number. If the serial numbers of received measurement

reports are not consecutive, there must be missing measurement reports, and the system

will make them up according to the interpolation algorithm.

As shown in the diagram, the network receives measurement reports n and n+4, whose

serial numbers are not consecutive, so the system will make up for the missing

measurement reports n+1, n+2 and n+3 with a certain algorithm.



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MR Filtering

MR

MRCon

tinuous

MRFlo

w

MRMR

MR

Filter----Average severalconsecutive MRs

MR

Filteringsmooth the instantaneous fading point

Calculate the average value within the filter window

When the network receives the measurement report, it can not judge the current condition of

MS according to just one measurement report due to the signal fluctuation. Therefore,

filtering, a more suitable method is applied.

Different filters are applied in receiving level, receiving quality and TA of uplink and downlink.



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Data Configuration of MR

Preprocessing

[MR Preprocessing]

Value Range: Yes, No

Default Value: No

Description: This parameter indicates whether the BTS pre-processes the MR.

This parameter determines the location where power control is performed. If this parameteris set to Yes, power control is performed by the BTS. Otherwise, the power control is

performed by the BSC.

When this parameter is set to No, the MR is processed by the BSC, in which case, both

Transfer original MR, Transfer BS/MS power class and Sent Freq of preprocessed MR are

invalid.

When this parameter is set to Yes, the load over Abis interface and that over the BSC are

reduced, thus shortening the response time and improving the network performance.

[Transfer Original MR]


Default Value: No

Description: This parameter indicates whether the original MR is transferred to the BSCafter the BTS pre-processes the MR.

When the parameter is set to Yes, the BTS transfers to the BSC both the processed MR and

the original MR.

Remarks:In case of 4:1 configuration, this parameter must be set to No if SDCCH/8 isgreater than 2.



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Preprocessing

[Transfer BS/MS Power Class]


Default Value: Yes

Description: This parameter indicates whether the original BS/MS power class is transferred

to the BSC.

Remarks:When MR pre-processing is enabled, uplink and downlink balance measurement is

affected if this parameter is set to No. In addition, power compensation handovers, such as

PBGT handovers, load handovers, and Concentric Cell handovers, may become abnormal.

[Sent Freq of Preprocessed MR]

Value Range: Do not Report, Twice every second, Once every second, Once every two

seconds, Once every four seconds

Default Value: Twice every second

Description: This parameter indicates the frequency that the BTS transfers the preprocessed

MR to the BSC. After the MR is preprocessed by BTS, the BTS transfers the preprocessed

MR to the BSC. For example, if this parameter is set to Twice every second, the BTS

transfers the preprocessed MR to the BSC twice per 0.5 second.



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Preprocessing

[Allowed MR Number Lost]

Value Range: 0~31

Default Value: 4

Description: This parameter indicates the number of MRs allowed to be lost in succession. When thisthreshold is not reached, the lost MR is estimated via the linear interpolation basing on the first and the

last MRs received. When this threshold is reached, all previous MRs are discarded, and calculations are

made again when new MRs are received.

Remarks: MRs fail to be decoded correctly when the signal strength in the serving cell is poor. Whenthis threshold is reached, all previous MRs are discarded and handover may fail. Thus, it is advised to

assign this parameter with a greater value to enable emergency handover.

[Filter Length for TCH Level]

Value Range: 1~31

Default Value: 4

Description: This parameter indicates the number of MRs used for averaging the TCH signal strength.

This parameter helps to avoid sharp drop of signal levels caused by Raileigh Fading and to ensure

correct handover decisions.

Remarks: When this parameter is too large, the impact of sudden changes is reduced, and the responseis delayed, thus affecting the network performance.

[Filter Length for TCH Qual]

Value Range: 1~31

Default Value: 4

Description: This parameter indicates the number of MRs used for averaging the TCH signal quality.



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Preprocessing

[Filter Length for SDCCH Level]

Value Range: 1~31

Default Value: 2

Description: This parameter indicates the number of MRs used for averaging the SDCCH signal strength.

It is recommended that you assign this parameter with a lower value because the SDCCH occupation

time is shorter than the TCH occupation time.

[Filter Length for SDCCH Qual]

Value Range: 1~31

Default Value: 2

Description: This parameter indicates the number of MRs used for averaging the SDCCH signal quality.

It is recommended that you assign this parameter with a lower value because the SDCCH occupation

time is shorter than the TCH occupation time.

[Filter Length for Ncell RX_LEV]

Value Range: 1~31

Default Value: 4

Description: This parameter indicates the number of MRs used for averaging the signal strength in neighboring cells.

This parameter helps to avoid sharp drop of signal levels and to ensure correct handover decisions.

Remarks: When this parameter is too large, the impact of sudden changes is reduced, and the response is delayed,thus affecting the network performance.

[Filter Length for TA]

Value Range: 1~31

Default Value: 4

Description: This parameter indicates the number of MRs used for TA averaging.



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General HO Process

MS Goes into New

Dedicated Mode

MS Goes into

Dedicated Mode

Measure and MeasurementResult Report

1

MR. Preprocessing2

Handover Judgment3


TA HO

Interference HO

Rx_Level_Drop HO

Bad Quality HO

Load HO

Edge HO

Layer HO

PBGT HO

AMR HO

No DL MR HO

Concentric Cell HO

MS Fast Moving HO


Penalty Processing

Ranking Processing

OM Forced HO

Direct Retry

Emergency HO

Normal HO



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Penalty Processing

Intra-cellHO

HO FailsEmergency(TA&BQ)HO

MS FastMoving

HO

ConcentricCell HO

Penalty

Punish on the

target cell

Punish on the

original cell

Punish on other high

priority layer cells

AMR HO

Fails

There are several kinds of penalty process

Penalty on target cell when a HO fails.

Penalty on source cell when an emergency HO (BQ and TA ) is performed.

Penalty on other high priority layer cells after fast moving HO is performed.

Penalty for concentric cell HO

Penalty for intra-cell HO

Penalty for AMR HO



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Penalty for Handover Failure

Punish the target cell when a HO fails.

This is to avoid the MS to select this cell again in next HO judgment.

Cell A

BTS

HO Fail

BSC

Cell B

BTS

When MS fails to handover to a target cell, a penalty will be given on the signal level of this

target cell during a so called handover failure penalty time period. That is, when ranking the

neighbor cells in the cell list, the corresponding neighbor cell with a failure record within the

penalty time will be penalized by cutting certain value on the reported signal level.



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Data Configuration of Penalty for

Handover Failure

[Penalty Level after HO Fail]

Value Range: 0~63

Unit: dB

Default Value: 30

Description: This parameter indicates the penalty level given to a target cell.

A penalty level is given to a target cell to avoid further attempts when a

handover fails due to any of the following reasons:

Cell congestion

A message indicating internal handover refusal is received.

A message indicating Um interface handover failure is received during out-going

BSC handover.

A message indicating Um interface handover failure is received during internal

handover.

Remarks: This parameter is valid only before the penalty time of handover

failure expires.



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Cell A

Cell B

BTSBQ&TA HO

BSC

Penalty for Emergency Handover

Punish the original cell when an emergency HO ( due to BQ andTA) occurs.

In case of BQ emergency handover, the original serving cell will be penalized (called signal

level penalty by BQ HO ), during BQ HO penalty time, to avoid MS to be handed back to the

original serving cell again within certain time.

It is the same for TA handover, i.e. the original serving cell is penalized (signal level penalty

by TA HO ) during TA HO penalty time.



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Emergency Handover

[Penalty Level after BQ HO]

Value Range: 0~63

Unit: dB

Default Value: 63

Description: This parameter indicates the penalty level given to the original serving cell where emergency handoveris performed due to bad quality. After emergency handover is performed due to bad quality, the receive level of the

original serving cell is decreased by the penalty level. Thus, other cells are given higher priority and handover to theoriginal serving cell is not allowed.

Remarks: This parameter is valid only before the penalty time of handover due to bad quality expires.

[Penalty Time after BQ HO (s)]

Value Range: 0~255

Unit: Seconds

Default Value: 15

Description: This parameter indicates the penalty time given to the original serving cell where emergency handoveris performed due to bad quality. During the penalty time, the receive level of the original serving cell is decreased by

the penalty level. Thus, other cells are given higher priority and handover to the original serving cell is not allowed.



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Emergency Handover

[Penalty Level after TA HO]

Value Range: 0~63

Unit: dB

Default Value: 63

Description: This parameter indicates the penalty level given to the original serving cell

where emergency handover is performed due to TA. After emergency handover is performed

due to TA, the receive level of the original serving cell is decreased by the penalty level.

Thus, other cells are given higher priority and handover to the original serving cell is not

allowed. This parameter is valid only before the penalty time of handover due to TA expires.

[Penalty Time after TA HO(s)]

Value Range: 0~255

Unit: Seconds

Default Value:30

Description: This parameter indicates the penalty time given to the original serving cell

where emergency handover is performed due to TA. During the penalty time, the receive

level of the original serving cell is decreased by the penalty level. Thus, other cells are given

higher priority and handover to the original serving cell is not allowed.



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Back? No way!Back? No way!

Umbrella

Micro cell

Penalty for MS Fast-moving Handover

Giving penalty on the other three layers(Non-umbrella Layer ) after MS

handovers to Umbrella cell by fast-moving-HO.

This is to keep MS staying in the umbrella cell and avoid frequent HO.

Purpose of such penalty: When MS crosses continuously several micro cells, it handover to

the umbrella cell with lower hierarchical priority level, to avoid too frequent handovers which

will affect the communication quality between those cells. At the same time, penalty is

started to avoid handover back to original cell again. A possible example is that a fast

moving car is running on a highway.



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Data Configuration of Penalty for MS

Fast-moving Handover

[Penalty on MS Fast Moving HO]

Value Range: 0~63

Unit: dB

Default Value:30

Description: This parameter indicates the penalty given to the level in a neighboring cell

when an MS is moving fast. Only the cells in the umbrella layer can give penalty to the cells

in other three layers.

Remarks: This parameter is valid only before the penalty time of fast moving expires.

[Penalty Time on Fast Moving HO]

Value Range: 0~255

Unit: Seconds

Default Value: 40

Description: This parameter indicates the period during which penalty is performed on the

neighboring cells of the fast moving MS. During this period, penalty on the neighboring cells

(on only the other three layers except the umbrella layer) of fast moving MS is valid.



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Underlaid

Overlaid Do not attemptagain duringpenalty time

after one failedHO(O->U)!

Penalty for Concentric Cell

A new concentric cell HO is prohibited within a penalty time after a

concentric cell HO failure.

Do notattempt againafter N failedHO(U->O)!

Huawei concentric cell HO failure means the failure of handover from the Underlaid to the

Overlaid, or from the Overlaid to the Underlaid.



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Concentric Cell

[Penalty Time after UtoO HO Fails(s)]

Value Range: 10~255 Unit: Seconds Default Value: 40

Description: After a UL to OL handover fails, no UL to OL handover

request is allowed before the penalty time expires.

[Penalty Time after OtoU HO Fails(s)]

Value Range: 0~255 Unit: Seconds Default Value: 10

Description: After an OL to UL handover fails, no OL to UL handover

request is allowed before the penalty time expires.

[MaxRetry Time after UtoO Fail]

Value Range: 0~8 Default Value: 3

Description: This parameter indicates the threshold of UL to OL handover

failures. UL to OL handover is not allowed if the number of handover

failures reaches this threshold.

Remarks: When this parameter is set to 0, not this threshold but the penalty

time restricts the permission of handover.



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Underlaid

OverlaidDo not

attempt backtoo fast!

Penalty for Enhanced Concentric Cell

A new UO HO is prohibited within a penalty time after a

OU HO is performed successfully.

This penalty is valid only for Enhanced Concentric Cell.



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Enhanced Concentric Cell

[Penalty Time of UtoO HO(s)]

Value Range: 0~255

Unit: Seconds

Default Value: 10

Description: This parameter indicates the penalty time for forbidding ping-

pong handovers. After an OL to UL handover is performed, UL to OL

handover is not allowed before the penalty time expires. If this parameter is

set to 0, a UL to OL handover is allowed when required.

Remarks: This parameter is valid only when Enhanced Concentric Cell is

allowed.



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Intra-cell HO

[Max Consecutive HO Times]

Value Range:1~20

Default Value: 3

Description: This parameter indicates the maximum number of consecutive intra-cellhandovers allowed. If the interval of two continuous intra-cell handovers is less than a

specified threshold, the two handovers are regarded as consecutive handovers.Intra-cell

handover is forbidden if the number of consecutive handovers exceeds this threshold.

[Forbidden Time after Max Times]

Value Range: 1~200

Unit: Seconds

Default Value: 20

Description: This parameter indicates the timer that starts when the threshold of maximumconsecutive intra-cell handovers is reached. Intra-cell handovers is allowed only when the

timer expires.

[Interval for Consecutive HO Jud.]

Value Range: 1~200

Unit: Seconds

Default Value: 6

Description: This parameter indicates the period for judging whether two continuous intra-cell handovers are consecutive.



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Data Configuration of Penalty for AMR

FRHR Handover Failure

[Penalty Time after AMR TCHF-H HO Fails(s)]

Value Range: 0~255

Unit: Seconds

Default Value: 30

Description: This parameter indicates the penalty time for AMR full rate to

half rate (FR-to-HR) handovers. Before the timer expires, no AMR FR-to-HR

handover request is allowed if the previous full-half handover fails due to

channel unavailability or channel mismatch.



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General HO Process

MS Goes into New

Dedicated Mode

MS Goes into

Dedicated Mode


1

MR. Preprocessing2

Handover Judgment3


TA HO

Interference HO

Rx_Level_Drop HO

Bad Quality HO

Load HO

Edge HO

Layer HO

PBGT HO

AMR HO

No DL MR HO

Concentric Cell HO

MS Fast Moving HO


Penalty Processing

Ranking Processing

OM Forced HO

Direct Retry

Emergency HO

Normal HO



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Ranking Processing

M rule

K rule

Basic ranking

16 bits ranking

Network feature adjustment

The ranking result: target cell selection of handover

Ranking processing of cells are major parts of the HO judgment.

The ranking result is used for target cell selection of handover.

The ranking processing includes:

Basic ranking

M rule

K rule

Network feature adjustment

16 bits ranking



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M RuleBegin

Finish to allneighbor cells?

An BSC external neighboringcell& the current channel is

SDCCH ?

No

Yes

Direct retry? [Inter-BSC SDCCH HOAllowed] is Yes?

Delete the cell from

the cell list?

If the cell flow is overload ?

Yes No

Yes

No

RX_LEV_DL(n) < [Min DL Power

on HO Candidate Cell](n)+

[Min Access Level Offset](s)?

RX_LEV_UL(n) < [Min UP Power on HO

Candidate Cell](s)+

[Min Access Level Offset](s)?

Delete this cell from

the cell list

Yes

No

No

No

No

Yes

End

For service cell:

Min Access Level Offset=0M rule will remove the neighbor

cells from the candidate cell listaccording to the flow.

Yes

Yes

M rule will remove the cells from the candidate cell list according to the

following conditions:

Under the condition of non-direct retry, if Inter-BSC SDCCH HO Allowed isNo, and

this is an external neighboring cell, and the current channel is SDCCH

If the cell is overload

RX_LEV_DL < Min DL Power on HO Candidate Cell + Min Access Level Offset

RX_LEV_UL < Min UL Power on HO Candidate Cell + Min Access Level Offset

For service cell:Min Access Level Offset is 0.



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Data Configuration of M Rule

[Inter-BSC SDCCH HO Allowed]


Default Value: No

Description: This parameter indicates whether an inter-BSC SDCCH

handover is allowed. An inter-BSC SDCCH handover is triggered when an

MS succeeds in requesting SDCCH but fails to request TCH in a BSC.



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Data Configuration of M Rule

[Min UP Power on HO Candidate Cell]

Value Range: 0~63 (-110 dBm to -47 dBm) Default Value: 10

Description: The M criterion supports the minimum value constraint of uplink received level of the

neighbor cell. Expected uplink level of the neighbor cell >= (the minimum uplink power of the

candidate cell for handover + the minimum access level offset)The M criterion is satisfied only when

the expected downlink level of the neighbor cell >= (the minimum downlink power of the candidate

cell for handover + the minimum access level offset).0-63 with 0 indicating -110 dBm and 63

indicating -47 dBm.

[Min DL Level on Candidate Cell]


Description: This parameter indicates the lower threshold of downlink receive level when a cell

becomes a candidate cell.

Remarks: This parameter must be appropriately specified. If it is too high, some desired cells may be

excluded from the candidate cells. If it is too low, an unwanted cell may become the target cell, thus

leading to handover failures or call drops. A cell can become a candidate cell only when the receive

level minus this parameter is greater than the minimum access level offset.

[Min Access Level Offset]

Value Range: 0~63 Unit: dB Default Value: 0

Description: This offset is based on the Min DL level on Candidate Cell. For different adjacent cells,

different offsets can be defined. Only when the receiving level of an adjacent cell > Min DL Level on

Candidate Cell + Min Access Level Offset, then this cell become a candidate cell.



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K Rule Flow of calculating K value.

Begin

Finish to calculatevalue K to all cells?

Serving cell?

K=0

No

K = RX_LEV (n) RX_LEV (s)

Yes

End

No

Yes

All the candidate cells are ranked in descending order according to the K value

A

F

E

D BC

Serving

Cell

Receiving

Level

Cell

Serving Cell

Cell ACell B

Cell C

Cell D

Cell E

Cell F

After the M rule , all the candidate cells are ranked in descending order

according to the K value

Service cell: K = 0

Neighboring cell: K = RX_LEV (n)RX_LEV (s)



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Network Feature Adjustment

After network feature adjustment, all the candidate cells have their

own 16 bits value.

The smaller the value is, the higher the handover priority and

position of the cell are in the candidate cell list, then it is possible to

be the candidate cell.

TheLowest

Weight

TheHighest

Weight 16 15 14 13 1

2 11 10 9

8 7 6 5

4 3 2

1



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The 1st~3rd bits

The bit value indicates the priority of downlink receiving level

according to the cell signal level and the penalty process taking place

beforehand.

The values come from max. 6 candidate cells and 1 serving cell

according to the level ranges from 000~110. The value for the cell

with the strongest signal level is 000.

141516 12345678910111213



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The 4th bit: Inter-cell HO hysteresis bit.

Note: In PBGT HO, whichever the greater of the inter-cell ( of the

same layer ) hysteresis and PBGT threshold, that value will be used

in the PBGT HO.

141516 12345678910111213

Is serving cell?

Always set to 0

No

RX_LEV_DL (n) >=

RX_LEV_DL (s) +

[Inter-cell HO hysteresis]

Yes

Set to 0Yes

Set to1

No

Service cell: always 0

Neighboring cell: when RX_LEV_DL (n) >= RX_LEV_DL (s) + Inter-

cell HO hysteresis, bit 4th is set to 0. Otherwise, set to 1



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Data Configuration of Inter-cell HO Hysteresis

[Inter-cell HO Hysteresis]

Value Range: 0~63

Unit: dB

Default Value: 5

Description: This parameter indicates the handover hysteresis between

adjacent cells of the same layer. The purpose of setting this parameter is to

reduce the "Ping-Pong" handovers. The value of this parameter is invalid if

cells are not on the same layer. 4 dB for populous urban areas and 8 dB for

suburbs.



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The 5th~10th bits

The bit value is decided according to their position in Huawei

hierarchical network structure.

Huawei cell layers can be divided into 4 layers and each layer can be

further divided into 16 different priorities.

So there are 64 different priorities in Huawei hierarchical cell structure.

141516 12345678910111213



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Hierarchical Cell Structure

GSM900 Cell

Micro Cell

Umbrella Cell GSM 900

GSM1800 GSM1800GSM1800

GSM 900

GSM900GSM900

GSM1800GSM1800

GSM1800 Cell

GSM 900

GSM900GSM900

GSM1800GSM1800

Layer 4low

Layer 3

Layer 2

Layer 1high

The handover algorithm of Huawei divides the whole network into four

layers, each of which further divided into 16 levels. The lower the layer

is, the higher the handover priority level will be. The Micro Cell layer

has the highest priority level.



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Data Configuration of Cell HierarchicalNetwork Structure

[Cell Layer]

Value Range:1~4 (mapping to the PICO layer, the MICRO layer, the MACRO layer, and the

UMBRELLA layer)

Unit: Layer

Default Value: 3

Description: The framework of Huawei network is divided into four layers: Umbrella layer, Macro

layer, Micro layer, and Pico layer. Each layer is designed with 16 priorities. The Umbrella layer refers

to the GSM900 layer with a large coverage area. It implements the high-layer coverage and the

connection of MSs moving at a high speed. The Macro layer carries most traffic on the GSM900 band.

The Micro layer carries most traffic on the DCS1800 band. It solves the problem of insufficient

resources. The Micro layer is a main cell layer for dual-band MSs in the future. The Pico layer is a

microcell layer on the GSM900 and DCS1800 bands. It meets the requirements for the provisioning of

traffic at hot spots and dead zones.

Remarks: You can set multiple priorities (a maximum of 16 priorities) for each layer. From the aspect

of traffic priority, if the layer and level of a cell is low, the priority is high.

[Cell Priority]

Value Range:1~16

Unit: Level

Default Value:1

Description: This parameter controls handover between cells at the same layer. Generally, the cells at

the same layer have the same priority. If the cells at the same layer have different priorities, the cell

with a smaller value has a higher priority.



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The 11th bit: The bit value is decided by cell-load-sharing criterion.

This bit is affected by 14th bit.

141516 12345678910111213

System load>=[System Flux Threshold for Load HO] or[Load HO Allowed ] =No ?

Yes 11th bit is

turned off

Is serving cell?

set to 0

NoYes

Cell load >= [Load

HO T hreshold](s)?

set to 1 set to 1

cell load >=[ Load Rep.

on Candidate Cell](n)?

set to 0

Yes

No

Yes

No

No

The 11th bit: bit value is decided by cell-load-sharing criterion. And this bit

will be turned off when the system load is higher than System Flux

Threshold for Load HO orLoad HO Allowedis set toNO

Service cell: if cell load >=Load HO Threshold, bit 11th is set to 1.

Otherwise, set to 0

Neighboring cell: if cell load >=Load Rep. on Candidate Cell, bit 11th is set

to 1. Otherwise, set to 0



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57/167




Data Configuration of Cell-load-sharing

[Load HO Threshold]

Value Range: 0~100(%)

Default Value: 85

Description: When the load handover is switched on, it is recommended that the Load HO

Threshold is set to 85.The cell load refers to TCH usage. When the cell load exceeds thevalue of Load HO Threshold, the BSC starts the load handover. That is, the BSC starts the

load handover after the TCH in the cell are proportionally occupied.

Remarks: Even if the Load HO Allowed is set to Yes, the Load HO Threshold and Load

Req. on Candidate Cell affect the queuing of the candidate cell handover. Therefore, when

the cell is overloaded, the handovers such as PBGT cannot be performed if this parameter

is not properly set.

[Load Req. on Candidate Cell]

Value Range: 0~100(%)

Default Value: 75

Description: If the cell load is lower than the value of this parameter, the cell accepts users

that are handed over to the cell due to their cell load. If the cell load is not lower than the

value of this parameter, the cell refuses the users.

Remarks: The same as that of Load HO Threshold



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Network Feature Adjustment 12th bit and 13th bit: Whether share the same BSC or MSC.

141516 12345678910111213

Is serving cell?NoYes

Both 12th and 13th set to 0

Different BSC:12th set to 113th set to 0

Is [Co-BSC/MSCAdj] yes?

See 14th bit

Yes

No

Co-BSC?

Co-MSC?

No

Yes

Different MSC:12th set to 013th set to 1

No

Yes

Turn off

12th &13th bit

The same BSC:12th set to 013th set to 0

12th bit: if neighbor cell is co-BSC with the serving cell, 12 th bit is set to 0. Otherwise,

set to 1

13th bit: if neighbor cell is co-MSC with the serving cell, 13 th bit is set to 0.

Otherwise, set to 1

Service cell: is always set to 0

These two bits will be turned off when Co-BSC/MSC Adj. is set toNO



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Data Configuration of Co-BSC&MSC

[Co-BSC/MSC Adj]


Default Value: Yes

Description: This parameter indicates whether the sequence of candidate

cells is adjusted. After the sequence is adjusted, the handover within the same

BSC/MSC takes priority.



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The 14th bit: Layer HO threshold adjustment bit.


141516 12345678910111213

The 15th/16th bits are reserved

Is serving cell?

set to 0

NoYes

Bit 14th set to 1, and bit

5th ~13th are turned off set to 0

Yes YesRX_LEV_DL >= [Inter-layer HOThreshold][Inter-layer HO Hysteresis]?

RX_LEV_DL >= [Inter-layer HOThreshold] + [Inter-layer HO Hysteresis]?

No No

The 14th bit: Layer HO threshold adjustment bit

Serving cell: RX_LEV_DL >=Inter-layer HO ThresholdInter-layer HO

Hysteresis, bit 14th is set to 0

Neighboring cell: RX_LEV_DL >=Inter-layer HO Threshold+Inter-layer HO

Hysteresis, bit 14th is set to 0.

If the above criterion is not met, then bit 14th is set to 1.

At the same time, bit 5th- 13th bits are turned off.

The 15th/16th bits are reserved



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Data Configuration of Layer HO

Threshold Adjustment

[Inter-layer HO Threshold]

Value Range: 0~63(-110 dBm to -47 dBm)

Default Value: 25

Description: In BSC handover algorithm, the M criterion is used to rank the handover

candidate cells. The M criterion includes 16 bits. This parameter is one bit of the 16 bits andit affects the rank of a candidate cell. When the downlink level of a cell is lower than this

threshold, the cell takes low priority as far as comprehensive sequence is concerned.

Remarks: Make sure that the receive level of the destination cell is higher than this threshold

in inter-layer handover or load handover. Otherwise, the MS may be handed from a cell with

heavy load and high level (high priority cell) to a cell with light load and low level (low

priority cell), thus leading to call drops.

[Inter-layer HO Hysteresis]

Value Range: 0~63

Unit: dB

Default Value: 3

Description: This parameter indicates the hysteresis of an inter-layer or inter-priority

handover. It is used to avoid inter-layer ping-pong handovers. Actual Inter-layer HO

Threshold of a serving cell = Inter-layer HO Threshold C Inter-layer HO hysteresis Actual

Inter-layer HO Threshold of a neighboring cell = Inter-layer HO Threshold + Inter-layer HO

hysteresis



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General HO Process

MS Goes into New

Dedicated Mode

MS Goes into

Dedicated Mode


1

MR. Preprocessing2

Handover Judgment3


TA HO

Interference HO

Rx_Level_Drop HO

Bad Quality HO

Load HO

Edge HO

Layer HO

PBGT HO

AMR HO

No DL MR HO

Concentric Cell HO

MS Fast Moving HO


Penalty Processing

Ranking Processing

OM Forced HO

Direct Retry

Emergency HO

Normal HO



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No DL MR HO

Serving Cell Neighboring Cell

When the quality of Um interface become worse and worse, it is

for the worse uplink quality that MS can not deliver downlink MR,

while the downlink quality is not bad enough for MS to receive the

downlink message normally.

Baduplinkquality

When the quality of Um interface become worse and worse, it is for the worse uplink

quality that MS can not deliver downlink MR, while the downlink quality is not bad

enough for MS to receive the downlink message normally. Under this kind of

urgency condition, in order to save this call, the network send handover command to

MS.



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Position of No DL MR HO

MS Goes into NewDedicated Mode

MS Goes into

Dedicated Mode

Measure and Measurement

Result Report1

MR. Preprocessing2

Handover Judgment3


TA HO

Interference HO

Rx_Level_Drop HO

Bad Quality HO

Load HO

Edge HO

Layer HO

PBGT HO

AMR HO

Concentric Cell HO

MS Fast Moving HO


Penalty Processing

Ranking Processing

OM Forced HO

Direct Retry

Emergency HO

Normal HO

No DL MR HO

Attention: After MR. Preprocessing, the No DL MR handover is triggered if trigger condition is satisfied.



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No DL MR HOBegin

Report 1 DL MR at lease?

Is [No Dl Mr. HOAllowed] Yes ?

= signal quality

filter length?

Yes

signal quality filter length:

For TCH:[Filter Length for TCH Qual]

For SDCCH:[Filter Length for SDCCH Qual]

No Dl Mr. in

current Mr.?

Yes

UL_Qua. (after filering)

>=[No Dl Mr.Ul QualHO Limit]?

Yes

Only one

cadidate cell?

>=[Forbidden timeafter MAX Times]?

Yes

No

No

No

Yes

Yes

No

No

[Intrecell HOAllowed]?

Yes

No

Triggering condition

No DL information in current MR

Stored UL Rx_Qual Value Number >=Rx_Qual Filter Length

UL Rx_Qual >=No DL MR HO UL Rx_Qual Threshold

Number of Lost DL MR < Cons. No DL MR HO Allowed Limit

Object cell selection

Prefer neighboring cell

If choose the service cell, it cannot in the penalty time for intra-cell handover.



66/167




Data Configuration of No DL MR HO

[No Dl Mr. HO Allowed]


Default Value: No

Description: This parameter is used to control the handover algorithm without downlink measurementreport. If this parameter is set to 0, the no handover algorithm without downlink measurement report is

disabled. Therefore, handover decision without downlink measurement report is not allowed in this cell.

If this parameter is set to 1, the no downlink measurement report handover algorithm is enabled.

Therefore, handover decision without downlink measurement report is allowed in this cell.

[No Dl Mr. Ul Qual HO Limit]

Value Range: 0~70 (mapping to RQ (0~7)10)

Default Value: 60

Description: This parameter indicates the uplink receive quality threshold of triggering an emergencyhandover when no measurement result on downlink channels is contained in the MR. The emergency

handover is allowed only when the filtered uplink receive quality crossed this threshold. When an

emergency handover is triggered, inter-cell handover takes priority. Intra-cell handover, however, is

triggered if no candidate cell is available and intra-cell handovers are allowed.

[Cons. No Dl Mr. HO Allowed Limit]

Value Range: 0~64

Default Value: 8

Description: This parameter indicates the upper threshold of consecutive MRs containing no downlinkmeasurement result for a call. Each call is configured with a global timer, which counts the number of

consecutive MRs containing no downlink measurement. When the timer exceeds this threshold, the

handover is disabled and the timer is reset.



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TA(Time Advance) HO


TA Threshold(s)

Time

TA(s)

HandoverTriggering

TA Threshold(n)

or

Handover Triggering ZoneTA(n)

Because a MS is far away from its serving BTS, the practice TA value is

more than TA threshold configured in data configuration, TA handover is

triggered.



68/167




TA(Time Advance) HO

Trigger

TA handover

Begin

The actual TA >=

[TA Threshold]?

Is [TA HO Allowed]

Yes ?

Any neighbour cell

exist?

Is serving cell?

Select the cell with the

highest priority in the

cadidate cell list

TA(n is in the same BTS)= TA Threshold


The cell must be of the highest priority in the candidate cell sequence and meet

the following restrictions.

Restriction

The service cell cannot be the object cell.

HO is not allowed when TA Threshold of the neighboring cell with the same BTS

is equal or smaller than that of the service cell.



69/167




Data Configuration of TA HO

[TA HO Allowed]


Default Value: Yes

Description: The parameter indicates whether a Timing Advance (TA)

handover is allowed. A TA handover is triggered when the TA is higher than

the triggering threshold. TA is calculated based on the distance between the

MS and the BTS. The longer the distance is, the greater the TA is.

[TA Threshold]

Value Range: 0~255

Unit: Bit period (A bit period corresponds to 0.55 km.)

Default Value: 255

Description: This parameter indicates the TA threshold of triggering

emergency handover. Emergency handover is triggered when TA is equal to

or greater than this threshold.



70/167




Interference Handover

Lev_Thr

Rx_Qual

RX_Lev

Qual_Thr

InterferenceOrigin


Handover Triggering

Zone

For a MS or a BTS, when the receiving quality is lower than the interference

quality threshold and receiving level is higher than the interference level

threshold, it is considered that interference exists in serving cell, so

interference handover is triggered.



71/167




Interference HOBegin

UL or DL receiving

Quality(s)>=A?

Is [Interference HO

Allowed] Yes ?

Any neighbour cell

exist?

Is serving cell?

Select the cell with thehighest priority in the

cadidate cell list

Rx_Level(n)>=[Inter-layer HO Threshold](n) +

[Inter-layer HO Hysteresis](n)?

Yes

No

End

No

No

Yes No

NoYes

None AMR FR:

A = RXQUALn, 1 RXQUAL8

9. Rx_lev is within [53,55], and Rx_qual > RXQUAL9



12. Rx_lev >= 63, and Rx_qual > RXQUAL12



72/167




Data Configuration of Interference HO

50>=63RXQUAL12

5159~62RXQUAL11

5256~58RXQUAL10

5353~55RXQUAL9

5449~52RXQUAL8

5546~48RXQUAL7

4042~45RXQUAL6

5739~41RXQUAL5

5836~38RXQUAL4

5932~35RXQUAL3

60=31RXQUAL2

70


73/167




Data Configuration of Interference HO

[Interference HO Allowed]


Default Value: Yes

Description: The parameter indicates whether an interference handover is allowed. An

interference handover is triggered when the receive level is higher than the receive threshold,

but the transmission quality is lower than the handover triggering threshold.

Remarks: Both downlink and uplink interference is judged, and inter-cell handover takes

priority. If no target cell is available, intra-cell interference handover can be implemented in

the serving cell if intra-cell handovers are allowed.

[RXQUAL1] ~ [RXQUAL12]

Value Range: 0~70

Description: Quality threshold 1~12 for the interference handover of nonCAMR FR voice

services. The value corresponds to (quality level 0~7) x 10.See the next slide

[RXLEVOff]

Value Range: 0~70

Default Value: 5

Description: The quality level offset of the interface handover of the AMR FR service

relative to non-AMR services or the AMR HR service (x 10).



74/167




Rx_Level_Drop HO

Rx_Level_Drop HO will be triggered when receiving level drops fast

because of barrier such as high building.



75/167


76/167




Data Configuration of Rx_Level_Drop HO

[Rx_Level_Drop HO Allowed]

Value Range: Yes, No Default Value: No

Description: The parameter indicates whether the emergency handover algorithm is allowed. The emergency handover algorithm isused to prevent call drops when the receive level of the MS drops rapidly. Generally this algorithm is not enabled until the

conditions are met. To enable this algorithm, original MR is required for the BSC.

[Filter Parameter A1~A8]


Description: Filter Parameter A1~A8 and Filter Parameter B work together to decide whether the rapid drop of the receive levelmust be reflected in one or multiple MRs. The conditions to trigger a rapid level dropping handover are as follows; In the algorithm

above, X1, X2, X3, X4, X5, X6, X7, and X8 indicate the uplink receive levels of the last eight MRs in the queue. Filter Parameter

A1~A8 must meet the following conditions: A1+A2+A3+A4+A5+A6+A7+A8=80. For example, if you want to reflect the rapid

drop of the cell level in a MR, you can set A3-A8 to greater than 10, A1 to 0, and A2 to 20.

[Filter Parameter B]


Description: This is one of the parameters that determine whether a handover is required due to fast dropping levels.This parameter

indicates the drop trend of the receive level within a period. The greater the parameter B is, a more rapid level drop is required for

triggering a rapid level dropping handover.See Filter Parameter A1-A8.

[Edge HO UL RX_LEV Threshold]


Description: The parameter indicates the uplink receive level threshold of an edge handover. An edge handover will be triggered ifthe uplink receive level is constantly lower than "Edge HO UL RX_LEV Thrsh." for a period longer than Edge HO Valid Time(s)

within Edge HO Watch Time(s). If PBGT handover is enabled, the corresponding edge handover threshold can be lowered. If

PBGT handover is disabled, this parameter must be properly specified to avoid overlapping coverage and channel interference. This

parameter should be adjusted based on the performance statistics and actual networks to achieve uplink-downlink balance.

Remarks: Edge handover uplink/downlink receive level threshold < Uplink/downlink signal strength lower limit of HUAWEI IIpower control



77/167




BQ(Bad Quality) HO

Begin

Is [BQ HO Allowed]

Yes ?

Any neighbour cell

exist?

Is serving cell?

Select the cell with the

highest priority in the

cadidate cell list

Yes

No

End

No

No

Yes

NoYes

Yes

UL_Rx_Q(s)>=[UL Qual.

Threshold]or DL_Rx_Q(s)

>=[DL Qual. T hreshold]?

RX_LEV_DL (n) >RX_LEV_DL (s)

+ Inter-cell HO hysteresis(s)

-BQ HO Margin(s) ?

[IntracellHO Allowed] yes

& cell notpunished?

Suitable cell

exist?

Trigger

BQ handover

Yes

Yes

Yes

No

No No

When the receiving level of a MS or a BTS is lower than the quality

threshold, bad quality handover will be triggered.

Triggering condition

UL receiving quality >= UL Qual. Threshold

OR DL receiving quality >= DL Qual. Threshold

For AMR call, the quality threshold is DL/UL Qual. Limit AMR FR/HR


The cells must be of the highest priority in the candidate cell sequence and meet

the following restrictions.

Restriction

Prefer neighboring cell. If the number of neighboring cell is more than one, it is

required that RX_LEV_DL (n) > RX_LEV_DL (s) + Inter-cell HO hysteresis -

BQ HO Zone

If there is no neighboring cell, handover can occur to the service cell, and the

channel at different frequency band, different MA, different TRX or different

channel (from left to right) is preference.



78/167




Data Configuration of BQ HO

[BQ HO Allowed]


Default Value: Yes

Description: The parameter indicates whether a Bad Quality (BQ) handover is allowed. BQ handover is triggeredwhen Bit Error Ratio (BER) over uplink/downlink channels is higher than the triggering threshold. If BER rises, or

signal strength drops, suspect that the signal power is low or channel interference increases.

Remarks: Inter-cell BQ handover is preferentially performed. If no target cell is available, intra-cell BQ handovercan be implemented in the serving cell if intra-cell handovers are allowed.

[DL Qual. Threshold]

Value Range: 0~70 (RQ (0~7) 10)

Default Value: 60

Description: This parameter indicates the downlink receive quality threshold of triggering an emergency handover.When the receive quality of the downlink is greater than DL Qual Threshold, an emergency handover is triggered.

When frequency hopping or DTX of the cell is enabled, it is recommended that you set this parameter to 70. When

an emergency handover is triggered, inter-cell handover takes priority. An intra-cell handover, however, is triggered

if no candidate cell is available and intra-cell handovers are allowed.

[UL Qual. Threshold]

Value Range: 0~70 (RQ (0~7)10)

Default Value: 60

Description: This parameter indicates the uplink receive quality threshold of triggering an emergency handover.When the receive quality of the uplink is greater than UL Qual Threshold, an emergency handover is triggered due to

bad quality. When frequency hopping or DTX of the cell is enabled, it is recommended that you set this parameter to

70.When an emergency handover is triggered, inter-cell handover takes priority. An intra-cell handover, however, is

triggered if no candidate cell is available and intra-cell handovers are allowed.



79/167





[DL/UL QuaLimitAMRFR]

Value Range: 0~70

Default Value: 65

Description: This parameter indicates the urgent switchover downlink/uplink quality controlfor the AMR FR service. The values of this parameter match quality levels 0-7 multiplying

10. The urgent switchover is triggered only when the downlink/uplink receiving quality of

the MS is greater than the switchover threshold, that is, the receiving quality is poor.

[DL/UL QuaLimitAMRHR]

Value Range: 0~70

Default Value: 60

Description: This parameter indicates the urgent switchover downlink quality control for theAMR HR service. The values of this parameter match quality levels 0-7 multiplying 10. The

urgent switchover is triggered only when the downlink receiving quality of the MS is greater

than the switchover threshold, that is, the receiving quality is poor.



80/167





[BQ HO Margin]

Value Range: 0~127 (-64 dB to +63 dB)

Default Value: 69

Description: A Margin in BQ handover algorithm used to judge whether to

perform BQ handover. When BQ Handover Allowed is set to Yes and Inter-

cell HO Hysteresis > "Inter-cell HO Hysteresis-BQ HO Margin", the Inter-

cell HO Hysteresis will act instead of the BQ HO Margin. When "Inter-cell

HO Hysteresis-BQ HO Margin" is assigned with a value smaller than 64, MS

can hand over to a lower level neighboring cell. 69 for popular urban areas,

72 for suburbs.

Remarks: If the data is updated from M900/M1800 BSC to HUAWEI

BSC6000,the default value of this parameter is 5.Then it's necessary tomodify the value of this parameter to 69,otherwise the BQ HO algorithm will

be invalid.



81/167




General HO Process

MS Goes into New

Dedicated Mode

MS Goes into

Dedicated Mode


1

MR. Preprocessing2

Handover Judgment3


TA HO

Interference HO

Rx_Level_Drop HO

Bad Quality HO

Load HO

Edge HO

Layer HO

PBGT HO

AMR HO

No DL MR HO

Concentric Cell HO

MS Fast Moving HO


Penalty Processing

Ranking Processing

OM Forced HO

Direct Retry

Emergency HO

Normal HO



82/167





Enhanced dual band cell is two different band cells which locate a

common site, and have the same azimuth.

Purpose

During the procedure of channel assignment and handover,

900M cell and 1800M cell can share their resource.

Assign the channel with low load in UL to MS preferentially.

Make MS handover from the high load cell to the low load cell.



83/167




Channel Assignment of Enhanced Dual Band HO

RX_LEV_OL>= [Incoming OL Subcell HO level Threshold(dB)] and

RX_LEV_UL RX_LEV (n) >[Distance Between Boundaries of UL and OL Subcells(dB)]Attention:

RX_LEV (n): RX_LEV of the strongest neighboring cell which has the same frequency band and layerwith underlaid subcell, but locates in a different BTS. If there is no such a cell, this value is -110dBmIf [ATCBHoSwitch] is [Close], the second condition is turn off.

A:

Beginfrom UL

[Assignment Optimization

of UL Subcell Allowed

or not] ?

Cell load of UL >[UL Subcell General

Overload Threshold(%)]?

Yes

A

Yes

No

Any idle TCH

Available in OL?

Assign TCH

in OL

YesNo

Yes

Assign TCH in UL

or direct retry identification

or queuing

No

No

TCH assignment (SDCCH channel in UL)

TCH assignment (SDCCH channel in underlaid)

IfAssignment Optimization of UL Subcell Allowed or not is set to NO, assign

TCH in underlaid as the normal assignment procedure

IfAssignment Optimization of UL Subcell Allowed or not is set to YES, assign

TCH in overlaid when the following conditions are met

Cell load of underlaid > UL Subcell General Overload Threshold

RX_LEV_OL >= Incoming OL Subcell HO level Threshold

RX_LEV_ULRX_LEV (n) > Distance Between Boundaries of UL and OL

SubcellsDistance Hysteresis Between Boundaries of UL and OL Subcell(dB)

RX_LEV (n): RX_LEV of the strongest neighboring cell which has the

same frequency band and layer with underlaid subcell, but locates in a

different BTS. If there is no such a cell, this value is -110dBm



84/167




Data Configuration of Channel

Assignment

[ATCBHoSwitch]

Value Range: Close, Open

Default Value: Open

Description: The switch of the ATCB handover algorithm.

[Assignment Optimization of UL Subcell Allowered Or Not]


Default Value: Yes

Description: This parameter indicates whether the access request originated in the underlaid subcell is

preferably assigned between overlaid subcell cell and underlaid subcell cell according to the Out Cell

Low Load Thred.

[UL Subcell General OverLoad Threshold(%)]

Value Range: 0~100

Unit: %

Default Value: 80

Description: If the ratio of underlaid subcell channel occupancy is greater than the value of this

parameter, some calls in the underlaid subcell are handed over to the overlaid subcell. Moreover, calls

originated in the underlaid subcell are preferably assigned to the channel in overlaid subcell.



85/167





Assignment

[Distance Between boundaries of UL And OL Subcells(dB)]

Value Range:0~63

Unit: dB

Default Value: 10

Description: This parameter indicates the distance between the overlaid subcell and

underlaid subcell. The value of this parameter is comparative. The greater the value is, the

longer the distance is. The enhanced dual-band network handover algorithm refers to the

boundary between underlaid subcell and overlaid subcell based on the comparative value of

signal strength of serving cell and neighboring cell. Suppose the signal strength of serving

cell is SS(s), and neighboring cell SS(n). If SS(s) is equal to SS(n), the cell is in the underlaid

subcell boundary. If the value of SS(s) - SS(n) is larger than the value of Distance Between

boundaries of UL And OL Subcells(dB), the cell is in the overlaid subcell.

[Incming OL Subcell HO Level Threshold(dB)]

Value Range: 0~63

Unit: dB

Default Value: 30

Description: This parameter indicates the lowest threshold of overlaid subcell level of the

handover from underlaid subcell to overlaid subcell. When the MS receive level is higher

than the value of this parameter, the BSC allows the handover of overlaid subcell cell.



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Begin

from OL

[Assignment Optimization

of OL Subcell Allowed or

not ] No ?

Cell load of UL= UL Subcell Lower Load

Threshold



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Assignm

huawei gsm handover algorithm

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